CryptoKitties

A cracking program was developedcracking program was developed which allows users to determine the exact genes of the offspring for a given 256 block time segment. If the user doesn't like that specific gene set they could wait 256 blocks and get another iteration based on the block hash and so on until they arrived at a desired gene set.

By December 3, 2017 more than $1 million dollars worth had been transactedhad been transacted through the game and was the most popular decentralized application on the Ethereum network, responsible for 15% of all traffic. The network congestion caused by the game highlighted the blockchain scalability issues for the Ethereum network and blockchains in general.

CryptoKitties is not a cryptocurrency. Instead it operates on Ethereum's underlying blockchain network, as a non fungible token (NFTNFT) unique to each CryptoKitty. Each CryptoKitty is unique and owned by the user, validated through the blockchain, and its value can appreciate or depreciate based on the market. CryptoKitties cannot be replicated and cannot be transferred without the user's permission even by the game developers. Users can interact with their CryptoKitties, having the ability to buy, sell, and sire (breed) them. A test version of CryptoKitties was unveiled at ETH Waterloo on October 19, 2017, the largest Ethereum hackathon in the world. As of December 2, 2017, Genesis, the first and highest selling cat was sold for 246.9255 ETH (~$117,712 USD) on that day.